Aluminum alloy and method of manufacture



Patented May 2 5, 1926.

UNITED STATES PATENT. OFFICE. I

HENRY KNEELAND RICHARDSON, OF NEWARK, NEW JERSEY, ASSIGNOR TO WESTING-HOUSE LAMP COMPANY, A CORPORATION QF PENNSYLVANIA.

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This invention relates to alloys of aluminum and more particularly tosuch alloys in which zirconium serves to neutralize the deleteriouseffect of certain impurities.

I An object of my invention is the produc-- tion of alloys of aluminumhaving high ductility, directly from impure aluminum ore.

' Another object of my invention is to simplify the manufacture ofaluminum, by using zirconium alloyed therewith, whereby it isunnecessary to purify the bauxite or other aluminum ore to obtain aproduct of high ductility.

A further object of my invention is the employment of zirconium to alloywith aluminum to neutralize the harmful effect-of impurities such asiron, which render it brittle and nonductile, and form an alloy ofgreater strength than heretofore produced without using zirc mium.

' A still further object of my invention is the simultaneouselectrolysis or reduction of impure bauxite and zirconium oxide toproduce an alloy of aluminum, zirconium and other metal impurities, theharmful effect of the impurities being neutralized by the zirconium.

Other objects and advantages will become apparent as the descriptionproceeds.

As is well known, aluminum is manufactured commercially by electrolysisof the fused ore and in order that the product may have ductility andnot be too brittle, it is B necessary when using ore containingimpurities such as iron, to carefully purify the-same;

According to the Heroult process, cryolite (Na AlF,) mixed with alumina(Al,() or 40 bauxite Al O 3H O) is fused in an electric furnace tweencarbon electrodes. num fluoride, calcium fluoride, sodium'chloride orother compounds, are sometimes'added to reduce the melting point of theelectrolyte and diminish the density, so as to facilitate theseparationof the'aluminum to the bottom of the fused bath. Any impuri ties in thealuminum ore, such as compounds of iron, will be reduced and alloy withthe aluminum, resulting in a brittle and nonductile metal. I a

In using aluminum ore or bauxite containing such impurities, it has beennecessary to submit the same to a careful and Alumi- Application filedNovember 5, 1928. Serial No; 672,717.

costly purification process in order to obtain aluminum having thedesired properties.

'According to my invention, I obviate the necessity of theusualpurification process by adding to the fused electrolyte, a materialwhich, upon reduction, furnishes a metal which neutralizes the effect ofimpurities such as iron.

My invention will be better understood by the more detailed descriptionthereof which follows.

In general, one of the usual commercial processes, such' as the Hall orthe Heroult process, may be employed for making alumities of compoundsof iron and silicon, may

be dissolved in the fused electrolyte, in such proportions, that themelting point thereof is a minimum or not excessively high, although theexact proportions used are not material. The proportion of alumina tocryolite or its equivalent in the mixture is preferably about 20% tosecure a minimum fusing temperature.

A small proportion of zirconium oxide or other zirconium compound may bemixed with the bauxite or alumina before dissolving the same in thefused electroylte in the furnace or added separately The exact amount orthe mannerof adding the zirconium oxide is not material, but it 'is notnecessary to use more than about,one-half percent of the total ofaluminum ore used and a smaller proportion than this may be employed'ifdesired, provided the proportion of impurities, such as iron compounds,are small. For larger proportions of iron compounds, the proportion ofzirconium oxide should be increased. y

Direct current is passed between the electrodes through the fusedmixture to electrolyze and cause reductionof the aluminum ore andzirconium oxide, which finally results in the formation of a moltenalloy of loy separates out at the .bottom of the furnace and ma beallowed to" run out through a tap hole tli any desired shapes.

As zirconium oxide is soluble in fused cryolite and. is more easilyelectrolyzed and reduced than alumina, the usual method of preparation,as-heretofore described, may be employed, merely adding a smallproportion of zirconium oxide prior to or during the reduction processfor the aluminum.

The function of the zirconium oxide is to provide a small proportion ofzirconium in the resulting'product to neutralize the harmful effect ofimpurities, such as. iron especially, and make it possible to preparealuminum alloys, which are substantially all aluminum, without thenecessity of purifying aluminum ore of deleterious substances, beforesubjecting it to electrolysis. That is, a smallproportion of zirconiumappears to neutralize a harmful effect of a much larger proportion ofiron in the alloy and results in as good or better metal than purealuminum.

An exampleof an alloy prepared according to my invention which is so-ductile and workable, that it was rolled into sheets .0015 thick, is asfollows:

Aluminum about 96.4%; iron about 2.6%; silicon about .7%: zirconiumabout .3%. Such an alloy, although containing a very small proportion ofzirconium, is much better than a corres onding alloy without zirconium,because t lacks brittleness, may be worked like andflis even strongerthan pure aluminum, having a tensile strength ofabout 18,000 pounds persquare inch before rolling. Without the zirconium content, such an alloywould be so brittle, that it would not be possible'to roll it or work itto a great extent.

With larger proportions of zirconium in the alloy, the increase instrength is more marked than with small amounts and the harmful effectsof much larger proportions of impurities may be neutralized. Forexamplean alloy prepared as above described,-

with the following composition:

Aluminum about 76%; iron about 13%; silicon about 2%; zirconium about9%, was found to have a Brinell hardness of about 166, indicating atensile strength correspond ing to that of steel or from 70,000 to80,000

lbs. per square inch.

Although giving specific examplesfof alloys prepared according toandmethods of practicing my invention, I do notwish to I be limitedthereto as they are merely illuserein and cast into pigs or in methodslike that described in detail and employed without departing from the'spirit and scope of my invention as defined by the appended claims.

What is claimed is: i 1. The manufacture of ductile aluminum- Zirconiumalloys comprising the electrolysis I of an unpurified bauxite mixturewith zirconium oxide, the proportion of zirconium alloy more than 10% ofzirconium, fusing the mixture in an electric furnace and electrolyzingout a ductile aluminum-zirconium alloy.

3. The method of manufacturing aluminum-zirconium alloys com risingmixin impure bauxite with asma proportion o zirconium oxide having azirconium .content insufficient to produce in the finished alloy .morethan 10% of zirconium, dissolving in fused cryolite and electrolyzingthe mixture in an electric furnace to form an impure aluminum with asmall proportion of zirconium alloyed therewith, whereby a strong andductile alloy is'produced.

{L'The method of manufacturing aluminum-zirconium alloys comprisingfusing alkali and aluminum fluorides, dissolving impure aluminumand'zirconium ores therein in such pro ortion as to produce an alloyhaving more t an aluminum, up to 10% of zirconium and the remainder ironand silicon and electrolyzing out such alloy,

5. The method of manufacturing alloys comprising fusing alkali, alkalineearth and aluminum fluorides, dissolving impure bauxite or the liketherein, dissolving zirconium oxide therein in such proportion as toproduce in the finished .alloy a zirconium content upto 10% andelectrolyzing out the aluminum-zirconium alloy- 6. An alloy of aluminumwithfdeleterious impurities and a small proportion of zirconium, thealuminum predominating and the zirconium being present in such quantitythat the harmful effect of the impurities-is neutralized.

-7. An alloy of aluminum, iron and zirconium the aluminum predominating.and the zirconium being present in such roportion that itneutralizes-the harmful e ect of the iron and a' ductile alloy issecured.

8. An alloy of aluminum, zirconium, silicon and iron with the aluminumpredominating and the zirconium being present only in sufficientproportion to neutr'alizethe effect of the silicon and iron to result inthe formation of a ductile metal.

' rat 9. An aluminum alloy comprisin from 2% to 13% of iron as impurityan being rendered ductile by containing zirconium in an amount less thanthat of the iron but sufiicient to neutralize the embrittling effect ofthe iron.

10. A ductile aluminum alloy of high tensile strength comprising about75% to 98% aluminum, about 2% to 13% of iron and zirconium in an amountless than that of the iron but'suflicientto neutralize the embrittlingeffect of the iron.

11. A ductile aluminum alloy comprising from 75% to 98% aluminum, from.13% to ll 2% of iron, .7 to 2% of silicon and from 9% to .3% zirconium.

1.2. An alloy of alummum, lron and Znstrength comprising 75% to num,about 13% of iron andabout 9% of ize the harmful' effect of; the ironand' strengthen the alloy.

13. An aluminum alloy 80% of alumizlrconium.

14. An aluminum alloy of im rov'ed strength comprising 75% to 80% oaluminum, about 13% of iron, about 2% of silicon and about 9% ofzirconium.

In testimony whereof, I have hereunto subscribedmy name this 2nd day ofNovember 1923.

HENRY-IRELAND RICHARDSON.

of improved-

